Leetcode102. Binary Tree Level Order Traversal二叉树的层次遍历
给定一个二叉树,返回其按层次遍历的节点值。 (即逐层地,从左到右访问所有节点)。
例如:
给定二叉树: [3,9,20,null,null,15,7],
3 / \ 9 20 / \ 15 7
返回其层次遍历结果:
[ [3], [9,20], [15,7] ]
class Solution {
public:
vector<vector<int> > levelOrder(TreeNode* root)
{
vector<vector<int> > res;
if(root == NULL)
return res;
queue<TreeNode*> q;
q.push(root);
while(!q.empty())
{
int size = q.size();
vector<int> temp;
for(int i = 0; i < size; i++)
{
TreeNode *node = q.front();
q.pop();
temp.push_back(node ->val);
if(node ->left)
q.push(node ->left);
if(node ->right)
q.push(node ->right);
}
res.push_back(temp);
}
return res;
}
};